Thin semiconductor card

ABSTRACT

The reliability of a thin semiconductor card, such as an IC card, is enhanced by stress absorbing part such as deformable part for absorbing externally applied stress, thereby preventing the stress from damaging the card main body, the semiconductor module, or the semiconductor elements. Alternatively, protection is provided by a weaker section, located away from the semiconductor module, that breaks under external stress before the stress can destroy the semiconductor module.

This application is a division, of application Ser. No. 026,873, filedMar. 17, 1987, now U.S. Pat. No. 4,764,803.

BACKGROUND OF THE INVENTION

This invention relates to thin semiconductor cards such as IC cardsincorporating semiconductor devices, and specifically to the structureof the card.

Thin semiconductor cards have a variety of configurations. Theconfiguration discussed below is that of the most common type of ICcard.

FIG. 5 shows an example of a prior art IC card, as shown for example inJapanese Patent Application Publication No. 6491/1978. The cardcomprises a thin semiconductor module 1 containing semiconductorelements, the card main body 2, and a set of electrode contacts 4through which electrical transfer of information to and from an externaldevice can take place.

An IC card of this configuration is used by inserting the card into anexternal device, which need only make contact with the electrodecontacts 4 to exchange electrical signals with the card via thecontacts.

Problems with the prior art thin semiconductor card result when the cardis externally stressed, as by bending, tension, or compression. Suchstresses have proved capable of breaking the semiconductor module ordetaching it from the card. In some cases stresses acting on thesemiconductor module have broken a semiconductor chip inside the module.

SUMMARY OF THE INVENTION

An object of the present invention is to solve these problems.

Another object of the invention is to provide thin semiconductor cardscapable of protecting the thin semiconductor module and its internalsemiconductor elements from destruction.

According to a first aspect of the invention, there is provided a thinsemiconductor card comprising a card main body and a semiconductormodule mounted therein, wherein the card main body is provided withstressabsorbing means that absorbs stresses resulting from externalforces applied to the card.

According to a second aspect of the invention, there is provided a thinsemiconductor card comprising a card main body and a semiconductormodule mounted therein, wherein a section of the card main body at alocation other that where said semiconductor module is disposed isweaker than that part of the card main body in which the semiconductormodule is provided so that when external force is applied, said weakersection will break before said semiconductor module is destroyed.

According to the first aspect of the invention, externally appliedstresses are absorbed by the stress absorbing means of the card, toprevent the stresses from destroying the card main body.

According to the second aspect of the invention, the semiconductorelements inside the semiconductor module are protected from destructionunder external stress by a structurally weak section of the card thatbreaks first, the weak section being located separately from thesemiconductor module.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1(a) and 1(b) are a plan view and a side view showing a thinsemiconductor card of an embodiment of the invention;

FIG. 1(c) is a side view of the card as externally stressed;

FIG. 2(a) is a plan view showing a thin semiconductor card of anotherembodiment of the invention;

FIG. 2(b) is a side view showing the card of FIG. 2(a) as externallystressed;

FIGS. 4 and 3 are plan views showing further embodiments of theinvention; and

FIG. 5(a) and 5(b) are a plan view and a side view showing a prior artthin semiconductor card.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention are described belowwith reference to the drawings.

FIG. 1 shows an embodiment of the IC card which comprises a card mainbody 2, which may be formed, for example, of a polyvinyl-chlorideplastic sandwiched between laminating materials. The IC card alsocomprises a semiconductor module 1 which is mounted in the card 2 andwhich contains a semiconductor element. The IC card further comprisesdeformable parts 3 extending in strips across the card main body 2 inlength and width directions. The deformable parts may consist of anelastic polymer rubber. The IC card further comprises a set of electrodecontacts 4 mounted on the surface of the semiconductor module.

Next, the function of the IC card will be described. Normally, when thecard is not acted upon by external forces, it presents a shape identicalto that of a conventional IC card as, shown in the plan and side viewsof FIGS. 1(a) and 1(b), and can be used like a conventional IC card byinsertion in an external device. If an external force such as a bendingstress is applied to the card in this state, the two deformable sections3 of the card absorb the stress by changing shape. FIG. 1(c) shows thestate when an external stress has been applied.

Since external stress is absorbed by deformation of the deformable parts3, the stress does not act on the semiconductor module 1 or the cardmain body 2. The module 1 and card main body 2 thereby protected fromdamage.

The invention is not limited to the embodiment described above, and canbe applied to any thin semiconductor card. The configuration andmaterials of the deformable parts are not limited in either material orshape to the polymer rubber sections shown in the above embodiment. Thelocations of the deformable parts are not limited to the locations shownin the above embodiment, and need not divide the card into fourquarters.

FIG. 2 shows a second embodiment of the present invention in which adeformable part 3 forms a ring around the semiconductor module 1. Thecard main body in this embodiment consists of two sections: a smallsection 5 surrounding the semiconductor module 1 and a larger section 6making up the rest of the card main body. The deformable part 3 arelocated between these two sections to absorb external stress, providingan effect similar to that of the first embodiment described earlier.

Although in the above embodiments the stress is described as beingabsorbed by deformable parts, stress may also be absorbed by amechanical member such as a hinged coupling.

Next, further embodiments of the present invention will be describedwith reference to FIGS. 3 and 4. As illustrated, in place of thedeformable parts 3 of the embodiments shown in FIGS. 1 and 2,corresponding portions 13 of the card main body is formed to be weaker,so that when external force is applied, the weaker portion 13 will breakfirst. If the card is made from a polyvinyl-chloride plastic laminatedon both sides, the weaker portion 13 may consist of the laminationsalone (without the polyvinyl-chloride layer). Other possible materialsinclude PMMA (polymethyl methacrylate), polyethylene, thermosettingresins (epoxy resins), and acrylic substances.

In this embodiment although the card itself breaks, the semiconductormodule and its internal components (such as memory and microprocessorchips) are undamaged. Accordingly, loss of information is prevented, andthe semiconductor module can be reused if mounted in another card.

In summary, the reliability of a thin semiconductor card of thisinvention is enhanced by a stress absorbing part such as a deformablepart 3 for absorbing externally applied stress, thereby preventing thestress from damaging the card main body, the semiconductor module, orthe semiconductor elements. Alternatively, protection is provided by aweaker section 13, located away from the semiconductor module, thatbreaks under external stress before the stress can destroy thesemiconductor module.

What is claimed is:
 1. A thin semiconductor card comprising:a card mainbody comprising a first section surrounded by a second section; asemiconductor module mounted to said first section; a deformablematerial surrounding said first section connecting said first and secondsections; whereby said deformable material absorbs stresses resultingfrom external forces applied to said card.
 2. A thin semiconductor cardcomprising:a card main body comprising a first section surrounded by asecond section making up the rest of said card main body; asemiconductor module mounted to said first section; a material that isweaker than said first and second sections surrounding and connectingsaid first and second sections; said weaker material absorbs stressesresulting from external forces applied to said card and breaks beforesaid first section containing said semiconductor module is stressedsufficiently to cause damage to said mounted semiconductor module.
 3. Athin semiconductor card comprising:a card main body comprising a firstsection and a second section; a semiconductor module mounted to saidfirst section; a flexible mechanical coupling connecting said first andsecond sections along their common boarder; whereby the mechanicalaction of said flexible mechanical coupling absorbs stresses resultingfrom external forces applied to said card.
 4. A thin semiconductor cardaccording to claim 1, wherein said deformable material is comprised ofan elastic material.
 5. A thin semiconductor card according to claim 3,wherein said flexible mechanical coupling is comprised of a hingedcoupling.
 6. A thin semiconductor card according to claim 1, wherein aset of electrode contacts are mounted on the surface of saidsemiconductor module.
 7. A thin semiconductor card according to claim 2,wherein a set of electrode contacts are mounted on the surface of saidsemiconductor module.
 8. A thin semiconductor card according to claim 3,wherein a set of electrode contacts are mounted on the surface of saidsemiconductor module.
 9. A thin semiconductor card according to claim 1,wherein said card's overall shape is substantially identical to that ofa conventional IC card.
 10. A thin semiconductor card according to claim2, wherein said card's overall shape is substantially identical to thatof a conventional IC card.
 11. A thin semiconductor card according toclaim 3, wherein said card's overall shape is substantially identical tothat of a conventional IC card.